Phomopsis twig blight and stem canker is becoming more common in Kentucky blueberry. Stressed plants are more susceptible to this disease, and reports are often associated with fields that have a history of Phytophthora root rot or severe abiotic disorder such as high pH.
Phomopsis Disease Facts
- Symptoms first appear in spring as blighted twigs that result in flower bud loss (Figure 1). Necrotic, reddish-brown lesions may develop around blighted areas and spread downward. Wilting and flagging is observed as stems die (Figure 2). Girdling cankers can often be observed lower on stems. Leaf spots can also occur on foliage, and fruit may ripen prematurely or rot.
- Disease is favored by warm, moist periods. Plants damaged by freezing temperatures or stressed by poor planting sites are more susceptible to disease.
- Caused by the fungus Phomopsis vaccinii.
- The pathogen survives winter in dead or infected twigs.
- Select resistant cultivars such as ‘Bluetta’ and ‘Elliott’
- Prune out infected twigs by cutting a minimum of 6 inches below infected tissue. Discard cuttings; never leave them in the field.
- Avoid planting sites prone to frosts.
- Maintain plant health with proper fertilization, irrigation, and weed management.
- Avoid wounding stems.
- Fungicides may be applied preventatively (before infection) beginning at bud break and continuing through full bloom for plantings with high infection risk. Homeowners may use fungicides that contain the active ingredients captan or propiconazole. Contact a county Extension agent for more information on fungicide use.
- Fungicides do not cure Phomopsis tip blight.
- Backyard Berry Disease &Pest Management Using Cultural Practices (with Low Spray, No Spray, & Organic Options) (PPFS-FR-S-25)
- Blueberry Diseases (PPFS-FR-S-10)
- Commercial Fruit Pest Management Guide (ID-232)
- Disease and Insect Control Programs for Homegrown Fruit in Kentucky (ID-21)
- Fruit, Orchard, and Vineyard Sanitation (PPFS-GEN-05)
- Midwest Blueberry Production Guide (ID-210)
By Kim Leonberger, Extension Associate and Nicole Ward Gauthier, Extension Specialist